Field of the Invention
The present invention relates to a technique for automatically deploying a ground spoiler that is provided at a main wing of an aircraft.
Description of the Related Art
Spoilers provided at a main wing of an aircraft are provided in order to reduce a lift generated by the main wing. The spoilers are generally divided into a flight spoiler that operates during a flight, a ground spoiler that operates in a running state at the time of takeoff and landing, and a multi-function spoiler that operates both during a flight and in a running state. In the present invention, the ground spoiler is used as a concept including the multi-function spoiler that operates in a running state as well.
The ground spoiler is a flight control surface mounted to a main wing, and is one of devices for reducing a lift of an aircraft. When the ground spoiler is deployed after the aircraft lands on the ground, the ground spoiler creates a stall behind the ground spoiler. The lift of the main wing is thereby reduced. In a case of an aircraft equipped with a turbojet engine, the ground spoiler functions as means for shortening a landing run distance of the aircraft after landing together with a thrust reverser (National Publication of International Patent Application No. 2011-504838). However, operations of the ground spoiler and the thrust reverser differ from each other in that the ground spoiler focuses on reducing a lift, and the thrust reverser focuses on increasing a drag.
In order to accomplish its object, the ground spoiler is designed so as to be deployed automatically, that is, without being controlled by a pilot after landing (e.g., “Practical Dictionary of Aviation Terms” edited by Public Relations of Japan Airlines, Asahi Sonorama, May 1997, p. 122). Conventionally, various standards have been employed for automatically deploying the ground spoiler. For example, the ground spoiler is automatically deployed on condition that a rotating speed (a wheel speed) of a wheel provided on a main gear reaches a prescribed value after the main gear touches down. However, if a runaway surface is wet or frozen and thus slippery, the wheel cannot rotate properly and may thus become locked. In this case, a pilot manually deploys the ground spoiler.
Thus, an object of the present invention is to provide a drive system which can automatically deploy the ground spoiler even when the wheel is locked.